Efficacy of conventional and sustained-release verapamil in stable angina pectoris

The efficacy of sustained-release (s.r.) verapamil and conventional verapamil were compared in a double blind, crossover study in 20 patients (age 53 +/- SD6 years) who had stable effort angina and had used betablockers and long acting nitrates for at least two weeks. All patients received s.r. verapamil 200 mg b.i.d. and conventional verapamil 120 mg t.i.d. in a randomised order for two weeks. A symptom limited bicycle exercise test was performed at the end of the patients' previous medication period with betablocker plus long acting nitrate and at the end of both verapamil treatments in the morning before drug administration and three hours thereafter. All the patients improved subjectively during both verapamil regimens according to NYHA classification and they had fewer anginal attacks. The time to onset of ST-segment depression during exercise remained shorter during beta-blockade and long acting nitrates than during both verapamil regimens (P less than 0.05). During the peak action three hours after drug administration conventional verapamil was most effective at comparable workloads (P less than 0.05), whereas the exercise time was slightly prolonged with s.r. verapamil before drug administration.